In recent years, various techniques for realizing high recording capacity of a magnetic disk device have been developed. One of the techniques is a recording technique called shingled write magnetic recording (SMR) or shingled write recording (SWR). The SMR magnetic disk device writes a subsequent recording track to overlap with a part of a track adjacent thereto (hereinafter referred to as an adjacent track) at the time of writing data to the magnetic disk. In the SMR magnetic disk device, a width of the overwritten track may be narrower than a width of a track that has not been overwritten.